Electrical resistor



June 27, 1939. j l MUCHER 2,163,797

ELECTRICAL RESISTOR Filed Jan. 2, 1936 T131. 32 22 Zr 23 \W N -L ia WINVENTOR Jamv J, Nana {WWW ATTO R N EYS Patented June 27, 1939 UNITEDSTATES PATENT OFFICE 2 Claims.

This invention relates to electrical resistors or voltage dividers whichare applicable in general to common electrical circuits and which areparticularly designed for use in radio receiving, transmitting andsignaling circuits. The advances which have been made in the present dayintricate and delicate radio circuits wherein minute balancing ofimpedance is indispensable, have created a demand for resistance unitsor voltage dividers of extreme accuracy and stability in order to complywith the precision required by the modern vacuum tubes and electronicdevices.

The invention primarily resides in an improved resistance unit orvoltage divider embodying a molded jacket of insulation material havinga low degree of moisture absorption and an improved method of producingthe same.

The invention comprehends a resistance unit or voltage divider which maybe of any desired length and with a plurality of conductor attachingtabs located in various positions throughout the length of the unit, inwhich the unit is embedded or encased in a molded jacket of insulationmaterial with the attaching tabs protruding from the jacket.

As a further object, the invention provides a resistance unit or voltagedivider which includes a plurality of resistance elements connectedeither in parallel or in series and arranged in either end to endrelation or superposed relation and embedded in a jacket of insulationmaterial which completely seals the same and provided with conductorattaching tabs extending through the Jacket and protruding therefrom.

As a still further object, the invention contemplates in a device of theindicated character, a heat conducting means associated with the moldedjacket of the unit for mounting the same on the apparatus with which theunit is used, which 40 functions to more rapidly dissipate the heatgenerated by the resistance unit within the jacket.

with the above recited and other objects in view, reference is now madeto the following specification and accompanying drawings in which therehas been disclosed, by way of example, several embodiments of theinvention, while the claims cover variations and modifications thereofwhich fall within the scope of the invention.

In the drawings:

Fig. 1 is a plan view of a resistance unit constructed in accordancewith the present invention.

Fig. 2 is an enlarged side view thereof with parts broken away and shownin section to disclose the 55 underlying structure.

Fig. 3 is a transverse sectional view taken approximately on the line3-3 of Fig. 2.

Figs. 4 and 5 are similar views showing slightly modified adaptations ofthe mounting means.

Fig. 6 is an end view of a modified form of jacket 5 construction.

Fig. '7 is a side view illustrating a further modification of theinvention; and

Fig. 8 is a perspective view of a plurality of resistance unitsconstructed in accordance with 10 the invention, illustrating the samein longitudinal alignment with the molded insulation jacket encasing andconnecting the units.

Resistance units of the type herein disclosed are intended to a largeextent to replace those types disclosed in prior United States LettersPatent Nos. 1,976,624, 1,982,475, 2,021,802, 2,036,071, 2,039,974 and2,046,129. These types of resistance units are manufactured withmounting centers which differ in length by fractions of an inch and 20which are produced in lengths from 1" to 10" with conductor attachingtabs having varying relative locations so as to fulfill the needs ofindividual requirements of the apparatus circuits in which the resistorsare incorporated. It is, there- 25 fore, apparent that if units withmolded insulation jackets were manufactured to conform to the individualrequirements of each user, special molds would be required with fixeddimensions of length, mounting apertures and allowance for 80 conductorattaching tabs. The cost of designing a special mold for each type ofresistance unit would be prohibitive when it is understood that thenumber of each particular type of resistance unit ordered at any onetime may be limited to 50 $5 or 1000 units and no further orderstherefor received.

While various methods differing in detail from each other may befollowed, it is preferred that in manufacturing a unit which embracesthe present invention an insulating jacket be molded in surroundingsealed relation to a number of resistance units by placing these unitsin a common mold cavity together with moldable insulation material. Careshould be taken to be sure that the units are spaced from the walls ofthe cavity and preferably from each other. Thereupon the insulatingmaterial which is preferably of the thermo-setting type is reduced to aplastic condition and compressed within the mold, so so that thismaterial is formed into a homogeneous mass completely encasing theunits.

Referring to the drawings by characters of reference, the resistanceunit illustrated in Figs.

1 to 3 of the drawings, which is of the wire wound 66 type, includes acore 23 of insulation material upon which is wound a resistance wire 2|of any desired diameter and which may be subdivided into any number ofpredetermined or fixed resistance values by means of a plurality ofconductor attaching tabs 22 preferably of a flat conducting material,one end of each of which embraces the resistance wire and core with theremaining free end protruding outwardly from the core. The unit thusdefined is embedded in a molded insulation jacket 23 which completelyencases the unit except for the portions of the conductor attaching tabswhich protrude therefrom. A mounting means 24 which is preferablyconstructed 0! a suitable metal or other material which functions torapidly dissipate the heat generated by the resistance unit within thejacket, is associated with the jacketed unit and as disclosed in Figs. 1to 3 of the drawings, the same consists of a flat sheet applied to thesurface of the jacket opposite to that from which the attaching tabsprotrude with side flanges 25 engaging the beveled side faces 26 of thejacket. One or'both of the opposite ends of the mounting means protrudesbeyond the end of the jacket and is apertured to provide attachingextremities 21.

In the form of the invention shown in Fig. 4, the side flanges 28 areillustrated as embedded and anchored within the insulation jacket 23,

while in the form of the invention shown in Fig. 5, the mounting means29 is attached to the insulation jacket 23 by keys 30 forming anintegral part of the jacket-and molded into key openings 3| formed inthe mounting means. In order to reenforce the jacket in the regionswhere the attaching tabs 22 protrude therefrom and to prevent warping ofthe structure, a longitudinal rib 32 .is molded integral with thejacket. In Fig. 6 of the drawings, a jacket is formed with a pinralityof longitudinal ribs or corrugations 33 which function as areenforcement and serve to minimize surface leakage by providing agreater surface area between the tabs and the ground; If desired, asshown in Fig. '7 of the drawings, the protruding extremity or ear 34 ofthe mounting means 24 may be disposed in a plane perpendicular to thatof the mounting means or plate.

It is of course obvious that any number of units in any desiredrelationship with respect to each other may be conveniently grouped andthese units may each have resistance wire or an equivalent of the sameor have different values and as shown in Figs. 1 and 2, that theterminals may be spaced as desired. Obviously, numerous other changes inconstruction and rearrangement of the parts might be resorted to withoutdeparting from the spirit of the invention as defined by the claims.

What is claimed is:

1. As an article of manufacture, a resistor including a plurality ofindependent resistance elements, connecting members having their innerends coupled to each of said elements, their bodies extending outwardlytherefrom, a jacket of molded thermo setting di-electric materialenclosing and intimately engaging all of said elements and the innerends of said members, and a continuousuninterrupted reinforcing ribexten'ding from substantially one end of said jacket to the other of thesame and common to all of said elements, said members extending throughsaid rib.

2. As an article of manufacture, an electrical resistor including aresistance element, a plurality of connecting members having their innerends secured to said element, their bodies pro jecting outwardlytherefrom, a molded thermosetting jacket enclosing and intimatelyengaging said element and the inner ends of said connecting members,said jacket being formed of di-electrio material, a continuousuninterrupted reinforcing rib extending from one end of said jacket tothe other end of the same and forming a part of said jacket and throughwhich the bodies of said members extend, a shell forming a base for saidresistor, and means forming a part of said shell and jacket andproviding an'interlocking keying structure to prevent movement of saidshell awayfrom the base face of said jacket.

JOHN J. MUCHER.

